(Mon 14 Sep 09)

It's described by its maker as "BMW's most innovative concept car ever", and you can see why. The Vision EfficientDynamics has, in the right circumstances, similar performance to the M3, yet, in other circumstances, it uses far less fuel than any current production BMW.

The Vision is a four-seat coupé with remarkably low aerodynamic drag (a co-efficient of 0.22, if you're interested) and downforce to create extra grip, all of it thanks to a system known as the Air Curtain which carefully channels air in a similar way, though not to the same extent, as an F1 car does.

The engine is a 1.5-litre three-cylinder turbo diesel, which doesn't sound like much for a car as dramatic-looking as this one. But it has an extraordinarily high maximum output of 163bhp, and it's not the only power source. The Vision is in fact a hybrid, with two electric motors, one producing up to 51bhp and driving the rear wheels while the other sends up to 80bhp to the front axle.

That 80bhp motor is rather special, though, because its output can be increased to 113bhp for 30 seconds and to 140bhp for 10 seconds. This means that, at least for short bursts, the Vision has a total output of more than 350bhp.

Assuming that you're driving more gently, which you certainly would if you were putting the Vision through the official EU fuel economy cycle, the combined fuel economy is estimated at 75.1mpg, which equates to 99g/km of CO2. Using the electric motors alone it emits no CO2 at all, and in answer to the inevitable question of "where does the electricity come from?" BMW has worked out that if it comes from a European power station the CO2 emissions will still be a mere 51g/km.

In all-electric mode the Vision is expected to have a range of 31 miles between charges, extending to 431 miles if the diesel engine is used too. Charging the battery pack is said to take two and a half hours using a conventional 220V power supply.

BMW has not gone so far as to say that the Vision will be built commercially, but there are several hints that something of the kind is being considered, including references to the 150-litre luggage compartment and a new form of the iDrive control system.

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